This invention relates generally to hydromechanical transmissions and, more particularly, to electronic control systems for hydromechanical transmissions.
Hydromechanical transmissions (HMTs) have been developed for vehicles to replace conventional automatic belt drive transmissions. In particular, HMTs have been developed for use with all-terrain vehicles (ATVs). The advantages of HMTs include increased power capacity, greater durability, and protection from environmental degradation. Even though the mechanical implementation and functionality of HMTs is very different from conventional belt-driven units, consumers prefer that vehicles drive and feel like conventional belt-driven units while still offering the advantages of HMTs.
Conventional belt drive transmissions use a centrifugal clutch or slipping belt to smoothly accelerate the vehicle from rest. Smooth startup conditions, however, are difficult to achieve with HMTs.
Another disadvantage of HMTs is the inability to react quickly to a dynamic operating environment. ATVs operate at a wide range of speeds, from creeping speeds to as fast as 90 km/hr. In addition, ATVs are used for a variety of functions, from racing to pulling heavy loads. Further, ATVs often are used on a wide variety of ground surfaces. HMTs often have difficulty reacting quickly to these factors, producing a harsher ride than conventional belt-driven units.
Yet another disadvantage of HMTs is the inability to react to operator-controlled braking systems. HMTs typically provide very little dynamic braking capability and therefore must be protected from overspeed during vehicle deceleration.
It is therefore a principal object of this invention to provide an electronic control system for HMTs that allows for smooth startup conditions.
A further object of this invention is to provide an electronic control system for HMTs that allows for quicker reaction to a dynamic operating environment.
Still a further object of this invention is to provide an electronic control system for HMTs that allows for an improved reaction to operator-controlled braking systems.
These and other objects will be apparent to those skilled in the art.